This invention relates to heat exchangers, and particularly to heat exchangers through which different fluids are passed, which if coming in contact with each other could result in fire, explosion or contamination of the fluids.
In many cases it is desirable to recover heat generated in a given process in order to improve the efficiency of the process. An example of such heat recovery would be the preheating of an air charge in a coal gasification process. Preheating can be accomplished by heat exchange in a conventional shell and tube heat exchanger. However, since the air could be at a higher pressure than the combustible process gas, any leakage could result in fire or explosion. In order to preclude the possibility of such a hazard, it becomes necessary to separate the fluids. Furthermore, in order to detect leakage of either fluid, which might escape to surrounding areas, means for detecting leakage is required.
In accordance with the present invention, the danger of violent reaction of the fluids has been alleviated by passing the fluids through different chambers, and providing for heat exchange through the use of heat pipes extending through each chamber. Leakage of either fluid can be detected through the use of a third chamber provided for passing a purge fluid. Means are provided for detecting leakage of either fluid in the purge fluid.